Title: Encryption/decryption device and method
Application Number: 200480020335 Application Date: 2004.07.06
Publication Number: 1823356 Publication Date: 2006.08.23
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: G09C1/00,H04L9/06
Applicant(s) Name: Sony Corp. Address:
Inventor(s) Name: Ito Yujiro, Shimosato Tsutomu
Attorney & Agent: di wankui huang xiaolin
Abstract:
     It is possible to perform encryption ensuring an excellent confidentiality and capable of completely coming back from an error. Input video data is calculated with pseudo-random numbers by an EXOR (100) and the encrypted data obtained is held by an FF (101) and reset by each line. Counters (102, 103) are incremented by each line and each frame and reset by each frame and a program head, respectively. An encryption device (105) encrypts outputs of an FF (104) for holding a fixed value, counters (103, 102) and the FF (101) by using a key (K) so as to generate pseudo-random numbers and divides a bit string by a shift register (106). The output of the shift register (106) and the input video data are calculated by EXOR (100) to obtain encrypted data. Since the encrypted output is fed back, it is impossible to perform stealing using the continuous input of the same data. Moreover, since the encrypted output which is fed back is reset by each line, it is possible to completely come back from an error.
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